Phase transfer techniques possess remarkable advantages for the synthesis of inorganic nanomaterials. In contrast to the abundant reports on the preparation of noble metal nanoparticles using phase transfer, the number of semiconductor nanocrystals syntheses based on phase transfer techniques is still limited. Herein, we report a systematic study of the phase transfer-based synthesis of HgS nanocrystals, including the tuning of their morphology/shape by either solvent choice or temperature. This strategy involves the transfer of Hg(II) ions from aqueous solution to toluene, oleic acid or oleylamine and subsequent sulfidation at room or elevated temperature. Furthermore, we have extended this phase-transfer based strategy to the fabrication of HgS-Au nanocomposites. The studies in this work might provide a facile route for producing HgS nanocrystals with desirable properties and offer an effective strategy to investigate the influence of the morphology of HgS on the physical/chemical properties of various HgS-based materials.